1. Field of the Invention
This invention relates to a composite membrane suitable for use in reverse osmosis processes such as for the desalination of aqueous solutions. More particularly this invention relates to a multilayer membrane in which one layer is poly-meta-phenylene tetrahydrofuran-2,3,4,5-tetracarboxamide, and one layer is a microporous support layer.
2. Prior Art
Permselective membranes suitable for use in desalination of aqueous solutions are the subject of numerous patents. Richter et al. U.S. Pat. No. 3,567,632 discloses membranes made of organic, nitrogen linked aromatic polymers. Cadotte U.S. Pat. No. 4,277,344 discloses permselective multi-layer membranes in which there is a microporous polysulfone substrate layer and a superposed polyamide layer made from an aromatic triacid halide and an aromatic diamine. Scala et al. U.S. Pat. No. 3,744,642 discloses multilayer membranes in which one layer is porous substrate and the juxtaposed layer is a polyamide, a polyphenylester, or a polysulfonamide. Weyland et al. U.S. Pat. No. 3,649,687 discloses the use of 1,3,5-cyclohexane tricarbonyl chloride in the production of cross linking agent: 1,3,5-cyclohexane triisocyanate. Hara et al. U.S. Pat. No. 4,353,802 discloses semipermeable composite membranes in which the membrane material is cross-linked using polyfunctional aromatic acid halides. Sundet U.S. Pat. No. 4,643,829 discloses semipermeable composite membranes in which there is a microporous polysulfone layer and a superposed polyamide layer made from interfacially polymerized poly-meta-phenylene cyclohexane-1,3,5-tricarboxamide.